216561520 has 80 divisors (see below), whose sum is σ = 577963008. Its totient is φ = 73923840.

The previous prime is 216561511. The next prime is 216561523. The reversal of 216561520 is 25165612.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216561523) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 151047 + ... + 152473.

Almost surely, 2^216561520 is an apocalyptic number.

216561520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 216561520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (288981504).

216561520 is an abundant number, since it is smaller than the sum of its proper divisors (361401488).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

216561520 is a wasteful number, since it uses less digits than its factorization.

216561520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1718 (or 1712 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 216561520 is about 14716.0293557739. The cubic root of 216561520 is about 600.5194760372.

The spelling of 216561520 in words is "two hundred sixteen million, five hundred sixty-one thousand, five hundred twenty".